Your main grow light- or primary grow light- can do a lot, but it has its limitations. Sometimes your plants can't get the full coverage or intensity they need. Or maybe it can't give them the wavelengths they need to thrive. Enter supplemental lighting.

Whether you're in a tent, in a warehouse, or even a greenhouse, grow rooms thrive with supplemental lighting. And the awesome thing about them is that they'll enhance yield size and quality.

The tricky part is knowing what you need and how to use it. But that's what this guide is for.

Here, we'll go over the importance of supplemental lighting, the various types of supplemental lighting, and how to use them to improve your yields. But first, let's talk about the best supplemental grow lights for your room:

1. Editors Choice

50 Watt Quad Band Advance Spectrum LED Grow Light Panel

$107.03 ⭐⭐⭐⭐⭐ (12 Reviews)

50 Watt Quad Band LED Grow Light Panel

When you're looking for a supplemental grow light that'll fill in the wavelengths your primary light leaves behind, this is the light you need.

It offers 4x wavelengths that target growth functions your main light won't: Dark blue (465nm) enhances continued root and leaf growth; deep red light (660nm) to boost meta-topolin production to keep plants green, lush, and promote flower growth; orange (620nm) to boost the yields of your fruiting and flowering plants; and white (6000k) for an extra boost of intensity.

And with a footprint of up to 4x3ft, this is perfect supplemental light for seedlings through harvest.

Perfect Supplement for Flowering & Fruiting Plants

Coverage Area: 3-12 Sqft.

Includes 4x Targeted Wavelengths for improved growth

Optimal Pairing: 400w+600w HID's / 200w-450w LED's / 24w-200w T5's

Great Primary Light for Houseplants

2. Best Vegging Growth

50 Watt Advance Spectrum All Blue LED Grow Light Panel

$72.95 ⭐⭐⭐⭐⭐ (6 Reviews)

50 Watt ALL BLUE LED Grow Light Panel

When you want more wavelengths that'll pump out lots of leaves, this is the light your plants need.

With over 400x 456nm diodes, this all blue LED grow light enhances photosynthesis. This increased in blue wavelengths means more leaf growth, which has 2 important effects: more light intake and increased flower sites. And with a footprint of 3-12 square feet, each of these lights is the perfect addition to each vegging plant you're growing.

So if you need stronger foliage growth, this grow light will give it to you for 20,000 hours at a mere 50 watts of power (that's less than most grow room fans!).

Perfect for Extra Foliage Growth

Increased Light Intake for Stronger Growth & More Flowering Sites

Coverage Area: Up to 12sqft

Optimal Pairing: Full Spectrum and Traditional Grow Lights

Perfect Primary Light for Clones & Seedlings

3. Best for Small Plants

24 Watt Advance Spectrum LED Grow Light Panels

Starting at $36.95 ⭐⭐⭐⭐⭐ (12 Reviews)

24 Watt LED Grow Light Panels

If you're working with clones, bonsai's, small flowers, or houseplants that aren't getting what they need with natural light, this is the supplemental light they need.

These 24w lights range from quad-band to tri-band lights, to all blue and all red lights. So these supplemental lights will enhance growth just like their larger counterparts, from foliage growth to flower and fruit production. However, its 4.5sqft coverage area is tailored to give off a stronger, more focused footprint onto smaller canopies.

So by combining this light with your primary light source, your smaller plants will thrive into larger ones.

Perfect Addition to Natural Light for Small Flowers, Clones, and Houseplants

Made to Increase Foliage & Flower Growth

Available in 4x Wavelength Combinations

Coverage Area: 4.5sqft

Optimal Pairing: Natural Light or Low Wattage Grow Lights

4. Widest Coverage

KIND X-Series LED Grow Light Bars

Starting at $119.95 ⭐⭐⭐⭐⭐ (0 Reviews)

KIND X-Series LED Grow Light Bars

When your primary light leaves weak spots on large canopies, this is the supplemental light your grow room needs.

Available in 2ft (X40) and 4ft (X80) options, this lights give off a even, 3-6ft wide footprint with an extra 110-160 PPFD of intensity. Compared to square panels narrow coverage and weak spots, these lights supplement your primary light evenly across wide canopies.

They also come in two spectrum combinations: vegging (with heavy blue, white, and easy red diodes) and flowering (heavy reds, orange, white, and blue). So no matter what stage of growth your plants are at, this supplemental light can cover wide canopies for bigger harvests.

Perfect for Flowering or Vegging Plants

Available in 2ft & 4ft Options to Suit Your Grow

3-6ft Wide Horizontal Coverage

110 (X40) -160 (X80) PPFD Intensity

Optimal Pairing: 400w-1000w HID's / 200-900w LED's

5. Strongest Supplemental Light

Horticulture Lighting Group 100 V2 QB192 Quantum Board LED Kits

$149 ⭐⭐⭐⭐⭐ (0 Reviews)

100w V2 QB192 LED Grow Light

When you're looking for a big burst of energy to supplement your primary light, this is the grow light your plants need.

With a PAR output of at least 420 PPFD, this light fills in gaps on light with intense coverage. It also offers coverage area of around 9 sqft, perfect for supplementing larger, mature plants. And with a color temperature of 5000k, your plants get every wavelength they need to thrive, from vegging through harvest.

Perfect for large grow rooms and big plants, this supplemental grow light is designed to give your grow an extra 16,000+ lumens while only using 95 watts of power.

Perfect for All Stages of Growth

Square Footage: 9 sqft.

Made with Samsung Doides for Extra Intensity and Lasting Power

420-620 PPFD Intensity

Optimal Pairing: 600w+1000w HID's / 300-900w LED's

What is Supplemental Lighting?

In the grow room, supplemental lighting is lighting that supplements the light coverage of your primary grow light. They fill in gaps of light your primary light leaves across plant canopines, including:

  1. Dark spots, such as the shaded growth toward the base of plants.
  2. Drop-off's in intensity, like on the outer edges of your primary light's footprint.
  3. Lack of vital wavelengths, like the low amount of red in MH bulbs.

When you fill in those gaps in coverage, you'll increase the quality of your plants and yields, too.

Supplemental lighting comes in T5, CFL, HID, and LED options. But hands-down, the most common and effective type of supplemental lights are LED grow lights. So we'll be focusing on those in this article.

Now that you know what we're talking about, it's time to move onto the importance if supplemental lighting in your grow room.

Advantages of Using Supplemental Lighting

Let's face it: most primary grow lights don't have everything plants need. Worse, doubling up on primary grow lights can overwhelm plants- not to mention use double the amount of energy to grow.

This grow room uses primary LED grow lights with supplemental lighting that's also LED.That's the main reason we use supplemental lights. But aside from keeping plants from harm, there are three main reasons all growers should use supplemental lights in their grow:

Increased Intensity & Coverage: Supplemental lights fill in those weak points of coverage across plant canopies. Even the most intense primary grow lights have a hard time penetrating deep onto leaves below the top of a canopy. And primary lights lose intensity the further their light spreads, leaving the plants on the outside of the light footprint starving for light. That uneven coverage will lead to smaller, less fulfilling yields.

So by adding supplemental lighting above, below, or on the sides of your growing area will help increase light penetration across your canopy. That increased intensity will lead to larger, higher quality harvests than before.

Enhanced Growth Properties: When a plant's nutrition and environment are on point but they're not getting the growth you're looking for- like lots of leaves or bigger flowers- your plants aren't getting the wavelengths of light they need to perform certain growth processes. Even when the intensity of your light is enough for photosythesis (i.e. growth), it's the abundance of particular wavelengths that helps particular growth functions like root or leaf growth.

For example, the blue wavelengths of light are responsible for chlorophyll production and strong, healthy stems and leaves. So if you're looking for more foliage growth that you're getting from your primary light, you can enhance leaf growth by adding an all blue or blue-forward grow light. In the same way, flower production can be acheived with extra red wavelengths, and IR and UV lights can enhance resin growth that your primary light can't acheive.

Bonus for Greenhouse Growers: Supplemental grow lights speed up the grow cycle of your plants. Changes in sunlight from season to season can really slow your harvests down if you’re relying completely on natural light. But when you introduce supplemental lights, you can easily speed up the grow cycle and even squeeze more cycles into a year than you would be able to otherwise.

The Best Types of Supplemental Lighting

When it's time to start looking for supplemental lighting, you'll have three types of lights to choose from: single band, multi-band (aka "traditional"), or full spectrum grow lights.

They all have their own unique qualities they offer your plants. And below, we'll describe what you'll be looking at, and explain the benefits of each on your plants:

Single Band Lighting

This is an example of an all blue single band supplemental grow light.

If you want to increase a specific growth property (like more foliage growth, faster flower blooming, or increased resin production) these are what you need.

Unlike other lights, these give you one specific wavelength of light designed to enhance specific growth patterns. You'll see all blue, all red, along with standalone UV and IR lights, too.

These are great at boosting a specific wavelength of light that your primary doesn't have an abundance of.

X They have limited spectrums, so only one property can be enhanced at a time.

Common Spectrums: All Blue, All Red, All UV, All IR

Multi-Band (Traditional) Lighting

This is an example of a tri-band (blue/red/white)  multi-band supplemental grow light.

Multi-band lights give plants multiple targeted wavelengths, enhancing multiple growth properties of their plants.

For example, dual band grow lights mix red and blue wavelengths to give plants a boost of foliage and flower growth at the same time.

These enhance multiple growth properties at the same, filling in gaps in wavelengths your primary light leaves.

X These require the most research, as you want to ensure you get the right wavelength combination for your plants.

Common Spectrums: Dual Band (red/blue), Tri-Band (red/blue/white), Quad Band (red/blue/orange/white)

Full Spectrum Lighting

This is an example of white, full spectrum supplemental  lighting.

Full spectrum supplemental lighting targets a broad spectrum of light to enhace intensity of your primary grow light.

To do this, these lights use white diodes. These white diodes contain virtually all wavevlengths of light. So while they may not enhance individual growth properties, they do a great job adding extra PAR across your grow room.

These are the best at boosting the PPFD intensity of your primary lights.

X They may not add anything to your plants other than intensity, so targeting specific properties of growth is not possible.

Common Spectrums: 3000k, 5000k, 6500k

Choosing the Right Supplemental Lighting

Now that you know what supplemental grow lights are and their benefits, it's time to start finding the best one for your plants.

This takes a three-pronged approach: finding the right wavelength(s) for your plants, finding the ideal intensity for your grow, and choosing the light with the best coverage area.

1. Choose the Right Wavelengths

This charge contains the vital wavelengths all plants need to thrive.

Blue wavelengths will lead to increased production and strength of leaf/foliage growth. More blue light means there's more leaves to capture light, as well as more flowering sites.

Red/orange wavelengths play two important functions: branch growth and strengthing, as well as flower and fruit stimulation. Strong branches can hold more leaves, flower, and fruit.

Violet wavelengths are high-energy wavelengths that increase chrlorophyll production to strengthen plant cells and enhance flavor/aroma properties.

White wavelengths of light contain all wavelengths of light, so it helps to intensify the wavelengths of light you're currently working with.

UV (ultraviolet) wavelengths help produce resins and essential plant oils. This will enhance flavors and aromas for fruit and flowers.

IR (infrared) wavelengths encourage plant stretching and growth. In the right amounts, this wavelength helps increase the speed your plant matures.

2. Finding the Optimal Intensity

This grower is holding a light meter in order to measure the amount of light they have and what they need to grow at optimal levels.

Next you have to figure out how strong your supplemental light(s) need to be.

Your primary light's doing the bulk of the work, so your supplemental lights don't need to be too strong. Each light should be around 25w-100w, which is around 45-175 PPFD.

So how do you know what size to get? It's easy as 1-2-3!

  1. Establish the ideal PPFD per plant.
  2. Find the points where that idea PPFD drops off. This can be above, below, or on the sides of your canopy.
  3. Choose the supplemental light with the PPFD to raise intensity to ideal levels.

For example, take a canopy that requires 600umol PPFD and you're working with a grow light that gives you a peak PPFD of 400umol.

You'll want a light that'll fill in the difference between the ideal PPFD and the drop-off, which is 200umol. So something like the 100w HTG light we feature would be ideal, as it'll give you up to 174 PPFD.

Note: If you're not able to fill in that gap 100%, don't worry. Start off getting as close as you can, then adjust lighting as needed.

3. Finding Optimal Coverage Area

The last part of the equasion is figuring out the coverage area you're looking for.

Intensity and wavelengths mean little if they're not covering as much space as you need. So it's vital to figure out the light footprint of each supplemental light you're going to use.

  • First, figure out how much of your drop-off you want to supplement.
  • Next, check out the supplemental grow light's coverage area. This is important, because you may need more than 1x light to fill in darkspots in large canopies.

With coverage and intensity in mind, choose the light(s) that give you the coverage you're looking for.

So for example, say you need to raise PPFD 150umol across 2 sqft. A 50w LED from Advance Spectrum could give you around 75umol with a coverage area of 3 sqft. You can pair two of these to both raise PPFD to optimal levels while covering the entire drop-off.

Alternatively, you can use a 75w light futher out from your canopy to help stimulate growth over a wider area.

How to Use Supplemental Lights in Your Grow Room

These are examples of side supplemental lighting, as well as lighting underneath plants.Now that you know how to find the right supplemental grow light, it's time to put them to work.

The most important part of this is remembering that you'll want to hang supplemental lighting with at least 12" of room between the canopy and the light. After that, it's all about finding the right position to mount them.

  • Mounting above plants will increase the intensity and wavelengths coming down from your primary light.
  • Mounting below plants will help light penetrate deeper onto shaded growth. This gives more uniform growth from top to bottom.
  • Mounting on the sides of plants helps expand and intensify the footprint of your primary light (like the picture here). This is especially helpful when the edges of your canopies, as light footprint loses intensity the further it spreads.

And once they're mounted, check in on them like you would with your primary light. Make sure they're not too close to your canopy, and of course be sure they're functioning properly.

Using Supplemental Grow Lights

If your primary plant grow light isn’t cutting it for your grow room - whether your plants aren’t getting the coverage they need or there’s a specific wavelength you want to provide them with - it’s time to add some supplemental lights into the mix.

Supplemental grow light make all the difference in your grow room. Even if you have a great primary grow light, there will always be instances when that light just won’t cut it. No matter what results you need from your supplemental grow light, there’s a whole range to choose from. Whether it's T5 or LED, single band to multi-band, supplemental grow lights provide the extra intensity and wavelengths your plants need to fluorish.

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